The multiple bones of a bluefin tuna head

Skull of a bluefin tuna (Thunnus thynnus, Scombridae)

Despite the more than 200 bones in the head, bluefin tuna is not the acanthomorph with the most complex skull anatomy. The skull of the remoras (Echeneidae), with a dorsal fin transformed in a sucker and extending onto the head, or the asymmetrical skull of flatfish (pleuronectiformes), or the flattened skull of a monkfish (Lophius piscatorius, Lophiidae) are few examples of higly modified skulls. But, because of their size, the bones of the skull of a bluefin tuna are good tools to learn to identify bony structures.

The different ostéologic layers, from the most superficial bones to intern ones, are here exposed, as they appear during an osteologic dissection.

The colour of the legends refers to the origin of the :
- in red : dermal bones,
- in blue : enchondral bones,
- in purple : bones of mixte origin (dermal and enchondral).